This invention relates to a system and process for increasing the combustible component content of a gaseous mixture containing such component, e.g. increasing the methane content of sewage digester gas containing methane and carbon dioxide.
Sewage digester gas (SDG), i.e. the gaseous product of digestion of sewage, includes principally methane (CH.sub.4) and carbon dioxide (CO.sub.2), in relatively high and relatively low concentrations, respectively. Methane (the major component of natural gas) per se has a relatively high fuel value, i.e. a high BTU release upon combustion. However, CO.sub.2 is noncombustible and its presence lowers the fuel value of SDG. It would be desirable to be able to efficiently and simply decrease the CO.sub.2 content and increase the CH.sub.4 content of gaseous mixtures including these materials as components, e.g. SDG, thereby increasing the fuel value of the mixture.
It has now been found that the aforesaid desirable ability is provided by the present invention.